18-3129373-G-C

Variant names:

• chr18-3129373-G-C
• rs764303814
• NM_003803.4:c.2653C>G

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 2P and 1B. PM2 BP4

The NM_003803.4(MYOM1):​c.2653C>G​(p.Pro885Ala) variant causes a missense change. The variant allele was found at a frequency of 0.0000031 in 1,613,868 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: 𝑓 0.000020 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: MYOM1 NM_003803.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 5.39
• Publications: 1 publications found

Genes affected

MYOM1 (HGNC:7613): (myomesin 1) The giant protein titin, together with its associated proteins, interconnects the major structure of sarcomeres, the M bands and Z discs. The C-terminal end of the titin string extends into the M line, where it binds tightly to M-band constituents of apparent molecular masses of 190 kD (myomesin 1) and 165 kD (myomesin 2). This protein, myomesin 1, like myomesin 2, titin, and other myofibrillar proteins contains structural modules with strong homology to either fibronectin type III (motif I) or immunoglobulin C2 (motif II) domains. Myomesin 1 and myomesin 2 each have a unique N-terminal region followed by 12 modules of motif I or motif II, in the arrangement II-II-I-I-I-I-I-II-II-II-II-II. The two proteins share 50% sequence identity in this repeat-containing region. The head structure formed by these 2 proteins on one end of the titin string extends into the center of the M band. The integrating structure of the sarcomere arises from muscle-specific members of the superfamily of immunoglobulin-like proteins. Alternatively spliced transcript variants encoding different isoforms have been identified. [provided by RefSeq, Jul 2008]

MYOM1 Gene-Disease associations (from GenCC):

• hypertrophic cardiomyopathy

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Uncertain_significance. The variant received 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.29990447).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_003803.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MYOM1	NM_003803.4	MANE Select	c.2653C>G	p.Pro885Ala	missense	Exon 18 of 38	NP_003794.3
	MYOM1	NM_019856.2		c.2506+2002C>G		intron	N/A	NP_062830.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MYOM1	ENST00000356443.9	TSL:1 MANE Select	c.2653C>G	p.Pro885Ala	missense	Exon 18 of 38	ENSP00000348821.4
	MYOM1	ENST00000261606.11	TSL:1	c.2506+2002C>G		intron	N/A	ENSP00000261606.7
	MYOM1	ENST00000582016.1	TSL:4	n.209C>G		non_coding_transcript_exon	Exon 1 of 3

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152160 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000724

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.00000802 AC: 2 AN: 249256 AF XY: 0.00000740

Gnomad AFR exome AF: 0.000129

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461708 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727136

African (AFR) AF: 0.0000597 AC: 2 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53400

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111868

Other (OTH) AF: 0.00 AC: 0 AN: 60374

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152160 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74330

African (AFR) AF: 0.0000724 AC: 3 AN: 41440

American (AMR) AF: 0.00 AC: 0 AN: 15274

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5188

South Asian (SAS) AF: 0.00 AC: 0 AN: 4830

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10620

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68016

Other (OTH) AF: 0.00 AC: 0 AN: 2094

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000756

ExAC AF: 0.00000827 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Uncertain:1

Mar 02, 2025

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.P885A variant (also known as c.2653C>G), located in coding exon 17 of the MYOM1 gene, results from a C to G substitution at nucleotide position 2653. The proline at codon 885 is replaced by alanine, an amino acid with highly similar properties. This amino acid position is conserved. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear.

Hypertrophic cardiomyopathy Uncertain:1

Oct 04, 2016

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, this variant is a rare missense change with uncertain impact on splicing. It has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may alter RNA splicing, but this prediction has not been confirmed by published transcriptional studies. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies. The frequency data for this variant (rs764303814) in the population databases is unreliable, as metrics indicate poor quality at this position in the ExAC database. This variant has not been reported in the literature in an individual with a MYOM1-related disease. This sequence change replaces proline with alanine at codon 885 of the MYOM1 protein (p.Pro885Ala). The proline residue is weakly conserved and there is a small physicochemical difference between proline and alanine.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.15
BayesDel_addAF	Benign	-0.052	T
BayesDel_noAF	Benign	-0.31
CADD	Benign	22
DANN	Benign	0.91
DEOGEN2	Benign	0.021	T
Eigen	Benign	-0.19
Eigen_PC	Benign	-0.0015
FATHMM_MKL	Benign	0.68	D
LIST_S2	Benign	0.61	T
M_CAP	Benign	0.0089	T
MetaRNN	Benign	0.30	T
MetaSVM	Benign	-1.1	T
MutationAssessor	Benign	1.0	L
PhyloP100		5.4
PrimateAI	Benign	0.38	T
PROVEAN	Benign	-0.77	N
REVEL	Benign	0.050
Sift	Benign	0.65	T
Sift4G	Benign	0.47	T
Polyphen		0.20	B
Vest4		0.57
MVP		0.73
MPC		0.13
ClinPred		0.16	T
GERP RS		4.8
Varity_R		0.15
gMVP		0.33
Mutation Taster		=81/19	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs764303814; hg19: chr18-3129371;